In order to protect an occupant in the driver's seat or the passenger seat of a vehicle in a collision or an emergency, cars having an airbag device that has an inflatable and deployable airbag and is installed in, for example, the steering wheel or the instrument panel are widely used. Furthermore, in recent years, in order to further enhance the function of protecting an occupant, including an occupant seated in the rear seat, a side airbag device that deploys an airbag in a curtain-like manner along an inner side wall window of the vehicle, between the window and the occupant, so as to cover the entirety thereof, is employed.
There is conventionally known an airbag device in which a folded airbag is stored at the upper edge of a window in a vehicle, the vehicle's interior side being covered with an airbag cover, and in which the upper part and lower part of the airbag are folded in different manners so that the airbag is quickly inflated and deployed along the inner side wall of the vehicle while suppressing protrusion toward the vehicle's interior side during inflation and deployment and that an occupant is more assuredly protected (see PTL 1).
In this conventional airbag device, the airbag is attached to a vehicle such that a main inflation portion on the lower edge side is roll-folded toward the vehicle's exterior side and a gas supply path portion continuous therewith, on the upper edge side, is folded in a non-roll-folded manner, which is easier to be deployed than roll-folding. By doing so, after the supply path portion of the airbag, to which gas flows in first, is quickly deployed and the airbag cover is push-opened, the roll-folding of the main inflation portion is unfolded and is deployed along the inner side wall of the vehicle. Thus, the occupant is received and restrained with this portion.
However, in this conventional airbag device, at the initial stage of deployment of the airbag, the supply path portion is inflated in the airbag cover, presses and push-opens the airbag cover toward the vehicle's interior side, and then pushes the roll-folded portion downward and deploys it. Therefore, the timing at which the roll-folded portion pops out of the airbag cover is delayed by the time necessary for the supply path portion to push-open the airbag cover and secure the exit port needed for the deployment of the roll-folded portion downward, which also delays the inflation and deployment of the airbag.
To counter this, conventionally, a roll-folded portion is disposed below (on the airbag cover side of) the non-roll-folded portion to cause the deploying non-roll-folded portion to push out the roll-folded portion downward, with which the airbag cover is push-opened, thereby quickening popping out of the roll-folded portion and inflation and deployment of the airbag. However, in this airbag, depending on the deployment state of the non-roll-folded portion, the direction in which the roll-folded portion is pushed out and is deployed may vary.
FIG. 7 includes schematic views showing examples of a conventional airbag device having such an airbag, in which the airbag before deployment and after starting to be deployed is schematically shown in cross section.
In this conventional airbag device 100, as shown, an airbag 110 (see FIG. 7A) includes a non-roll-folded portion (bellows portion) 111 that is folded in a bellows manner on the upper edge side, and a roll-folded portion 112 (illustrated as a circle in the figure) that is roll-folded on the lower edge side. The upper edge of the bellows portion 111 is attached to the upper part of the vehicle's side wall (not shown). Furthermore, the airbag 110 starts to be deployed from the bellows portion 111 by the gas supplied from an inflator (not shown). The deploying bellows portion 111 pushes and presses the entirety of the roll-folded portion 112 downward.
At this time, in this airbag device 100, due to the folding shape of the bellows portion 111, the error or fluctuation of the relative position between the bellows portion 111 and the roll-folded portion 112, or the like, the direction in which the bellows portion 111 is deployed may vary (see FIGS. 7B and 7C). This may vary the direction in which the roll-folded portion 112 is pushed out in both directions in the vehicle's width direction (see arrows Y1 and Y2 in FIGS. 7B and 7C) and may fluctuate the direction in which the roll-folded portion 112 pops out of the airbag cover (not shown). As a result, in this airbag device 100, the deployment direction of the airbag 110 (in particular, the deployment direction at the initial stage of inflation and deployment) may vary, leading to a failure to sufficiently ensure stable deployment properties of the airbag 110.